New Antarctic findings of Upper Cretaceous and lower Eocene loons (Aves: Gaviiformes)

ACIOSTA HOSPITALECHE, CAROLINA; GELFO J. N.

ANNALES DE PALEONTOLOGIE

MASSON EDITEUR

Lugar: Paris; Año: 2015 vol. 101 p. 315 - 324

0753-3969

tThe new remains of Gaviiformes collected from the Maastrichtian Sandwich Bluff Member (López deBertodano Formation in Vega Island), the Maastrichtian Klb 9 (López de Bertodano Formation in SeymourIsland), the Maastrichtian Snow Hill Formation (Vega Island), and the Ypresian Submeseta Formation(Seymour Island), Antarctica, are described. A specialized foot-propelled diving morphology is alreadypresent in the Antarctic Polarornis gregorii, the Chilean Neogaeornis wetzelli and the new specimens herereported, suggesting that such diving skills were developed at least since the Upper Cretaceous. Theoccurrence of Gaviiformes in the Southern Hemisphere during the Upper Cretaceous?lower Eocene timesis consistent with recent phylogenetic proposals relating this group to Sphenisciformes and Procellari-iformes, birds already recorded in Antarctica. The fossil record also supports the idea that the hemispheredisplacement observed in Gaviiformes could be a response to increasing competition for resources withSphenisciformes. The phylogenetic proximity of penguins and loons plus their similar trophic behav-ior, suggest that competitive exclusion could have triggered the gaviiform migration to the NorthernHemisphere and explain their extinction from Southern continents.